1. Field of the Invention
The invention relates to a process and an apparatus for obtaining strip specimens from the area of the strip tabs of strips wound into coils for material inspection.
2. Description of the Prior Art
It is known in the art of metal rolling that certain rolling stresses are imposed during the rolling operation, on the material being rolled. This is generally true of all rolling operations, and it is desirable to know the degree of the rolling stress so as to make an allowance for the same in any future processing or fabrication of the rolled material.
In a process where the rolled material is formed into wound or rolled coils, it is easy enough to subject the rolled material to stress-analysis, by taking a sample length of the rolled material from the exterior or outermost end of the wound coil. However, it is found in practice that rolling stresses imposed on elongate material which is rolled, will almost always vary from the region of the inside tab of the wound coil through a middle region of the wound coil to the outermost region of the wound coil. For this reason, if a sample is taken from the outermost region per se of the wound or rolled coil, which region of the coil is most accessible, any data obtained from analyzing a sample from the outermost region will not represent the stress level of the rolled material in the region of the inside tab of the wound coil.
Also, experience has shown that the extraction of only one specimen on the external circumference of a metal strip which has been wound into a coil does not always give sufficient information on the quality of the entire coil.
The distribution of the exceeding limit of elasticity over the length of the strip is not uniform, because of the processes to which the strip has been subjected. As a rule, the exceeding limit of elasticity of the inside strip tab is greater by a predetermined amount than that of the outside strip tab of the strip wound into a coil. By the precise determination of the limit of elasticity at the beginning of the coil, for example, of the inside strip tab, it is possible to reduce the maximum limit of elasticity. Also, among other things, it is also possible to reduce the costs for the production of hot-rolled wide strip, for example, by using smaller quantities of alloy elements. Basically, it is possible to take and examine specimens at any point over the length of the strip, if the strip has previously been unwound. However, it should be noted that especially with fairly great strip thicknesses and/or with wide high-strength hot-rolled strips, this method cannot be used because such strips cannot be economically wound again after the specimen has been removed.
Hitherto, whenever a sample of the coiled material was required to be taken out from the inside of a wound coil, access to the coil inside was unobtainable in coils with relatively small inside diameters. Samples had to be obtained by opening out or unrolling the coil and re-rolling the coil after sampling. While such an operation satisfied the sampling requirement, the overall process suffered from lack of economy and lack of efficiency in production.
There has been an unfilled need for a process and apparatus wherein a sample from the inside tab region of a wound coil of metallic material may be automatically obtained in a short period of time without opening the coil for obtaining a sample specimen for inspection.